In dyeing of human hair with direct dyes as distinguished from oxidation dyes, the resultant final color is a combination of the natural hair color plus the color added by the dye. Where oxidation dyes are utilized and the hair is to be dyed a shade that is lighter than the shade of the person's hair, the dyeing procedure first eliminates the natural shade of the hair through bleaching with an oxidizing agent such as alkaline hydrogen peroxide. Then the desired shade is obtained on the hair by contacting it with the oxidation dye. Colored polymeric compounds of high molecular weight are produced on the hair by the action of atmospheric oxygen or by oxidizing agents such as hydrogen peroxide. It is also possible to simultaneously bleach and color the hair. In such cases hair is concurrently bleached by alkaline hydrogen peroxide as dyestuff penetrates into the hair and is oxidized to produce the desired color.
When oxidation dyes are used in the dyeing of human hair, the procedure usually involves the use of a two part system. One part is the lotion formulation which contains a variety of ingredients including the oxidation dye precursor chemicals which when mixed with the second part, the developer formulation, prior to application to the human head, causes the formation of the desired colored dyes. The developer usually contains an oxidizing agent such as hydrogen peroxide or a peroxide precursor. If sufficient peroxide is used, some of the natural melanin pigment of the hair may be destroyed first and the colored dyestuffs formed by oxidative coupling of the precursors in the first part, penetrate into the hair to give it the desired color. Such systems will generally contain 50% or more of organic solvents and surfactants, and require relatively high levels of dye to produce the desired color.
In practice surfactants are normally used to thicken the hair dye compositions to a more viscous consistency which will prevent the composition from running off the hair during use. The surfactants are dissolved in organic solvents. When the aqueous developer is added to the lotion, the water dilutes the organic solvents and the surfactants come out of solution and will thicken the composition.
It is also known from patents to use certain polymers in the developer to provide viscous solutions of hydrogen peroxide, however a number of well known cosmetic thickeners are not stable in hydrogen peroxide solutions. Furthermore, thickening of the solution is desirable only after the lotion and developer parts have been mixed together.
U.S. Pat. No. 4,130,501 discloses the use of various Carbopol resins for preparing thickened hydrogen peroxide formulations. These formulations were found to be stable when the solutions were made alkaline with sodium hydroxide. However, they are stable in storage only as thickened alkaline gels and are applied in that form.
U.K. patent No. 827,331 discloses the use of certain polymers, including copolymers of methacrylic acid, as thickeners for hydrogen peroxide in bleaching of hair. The formulations in the patent are described as thick gels over a pH range of 3 to 8 and are applied to hair in the thick condition. A thickened peroxide composition, such as is described in this reference would not be useful for oxidation dyes because it would be difficult to mix with the dye solution.
U.S. Pat. No. 4,313,932 discloses a dry, powder composition for admixture with water to provide a hair bleaching composition. The reference also discloses use of certain acrylic polymers to thicken peroxide formulations after water is added. The thickener used in this reference is part of the powder composition which is added to the peroxide immediately before use. Stability of the thickener to peroxide during storage is not a consideration as the product is a dry powder.
Several conditions are important for the procedures using oxidation dyes to work properly. First and foremost, stability of the formulations is imperative, particularly if the product is to be packaged and marketed. Secondly, mixing of the two parts should be quick and easy. Thirdly, after mixing, the resultant thickened solution should have the properties of being easily applied to the head and thick enough to remain on the hair until the dyeing process is complete and removal can take place.
Accordingly, it is an object of the present invention to provide a stable, oxidation dye formulation. It is a further object of the present invention to provide a two part dye composition which can be readily mixed and easily applied to the hair. It is still a further object of the present invention to provide an oxidation dye composition which is thick enough to remain on the hair until the dyeing process is complete. It is yet another object of this present invention to provide a two part dye composition containing substantially lower amounts of solvents, surfactants and dye than has generally been heretofore employed.